Lid for an aluminum beverage can

ABSTRACT

A can lid ( 14 ) for an aluminum beverage can comprises a pull tab ( 38 ). Further, it has a chuck wall ( 26 ) defining a plug diameter, a countersink ( 28 ) and central panel ( 30 ) having a panel radius ( 48 ). On the central panel, a score line ( 34 ) defining a tear panel ( 32 ) and a rivet ( 40 ) for connecting the pull tab to the can lid are arranged. The plug diameter is between 45 to 49 mm, an outside lid diameter is between 52 to 55 mm and a lid weight is less than 1.9 gr. The central panel has a thickness of less than 0.19 mm. The score line defines an area of between 300 mm 2  to 350 mm 2  and the score line has a shortest distance from the panel radius of less than 3 mm.

The invention refers to can lids for two-piece aluminum beverage cans.

The invention refers to two-piece aluminum beverage cans with a unitaryDWI can body and can lid with a pull tab.

Two piece beverage cans comprise a can body made from one piece ofaluminum sheet metal and a can lid with a pull tab affixed to the canlid. A score line in a panel of the can lid defines a tear panel thatcan be opened by means of the pull tab. The pull tab can be astay-on-tab that opens a hinged tear panel. In prior art cans, the pulltab is affixed to the can end by a rivet that is formed from the sheetmetal of the can lid. Can lids are also known as can ends.

The can body is a drawn and ironed (DWI: drawn and wall-ironed) can bodythat is produced by first drawing an aluminum blank into a cup and thenironing the walls of the cup to form the can body. The can body has anopen end with a reduced diameter. The reduced diameter of the can body'sopen end is achieved by way of necking the can body in a necking machinein which the diameter of the open end is reduced in several stages.

Prior art cans often have a body that is cylindrical along the largestportion of its longitudinal extension. A typical diameter of prior artaluminum beverage cans is 66 mm. These cans are named 211 cans in theindustry.

After filling of a can body e.g. with a carbonated beverage, arespective can lid is attached to the can body by way of a folded doubleseam. The can lid has a smaller diameter than the can body.

To match a respective can lid, the can body diameter at the can body'sopen end is reduced from 66 mm to the fitting diameter for the can lid,e.g. ˜57 mm (206), 55 mm (204), 52 mm (202) or 50 mm (200) by way ofnecking.

A typical can body has a base and a cylindrical side wall that extendsupwardly from the base and that has a wall thickness in the order of 94to 97 μm for a can having a diameter of 66 mm. A can having a diameterof 58 mm typically has a wall thickness in the order of 90 to 94 μm. Thecan body further has a tapering neck that extends upwardly from thecylindrical side wall and that defines the reduced diameter open end ofthe can body prior to seaming. The can body's open end has a smallestinternal diameter called plug diameter, which approximately matches themetrical dimension of the can lid, e.g. 52 mm.

The ratio between the can maximum diameter and the plug diameter that isachieved by way of necking is called necking ratio. The base includes astanding ring and a dome arranged within the standing ring.

The can lid is made from sheet metal aluminum and has a central panelwherein the rivet and the tear panel are arranged. The central panel iscircumferentially surrounded by a countersink that in turn iscircumferentially surrounded by an upwardly extending leg, e.g. a chuckwall. At the outer end of the upwardly extending leg, a curl is arrangedthat eventually is folded to form the seam that connects can body andcan lid and that defines the lid outside diameter. The can lid's chuckwall defines a plug diameter of the can lid.

On the central panel, a rivet for connecting a pull tab and a tear paneldefined by a score line are arranged. The tear panel an be opened bymeans of the pull tab that breaks the score line, when a handle part ofthe pull tab is lifted and thus an opening part of the pull tab ispressed on the tear panel next to the score line. Between the handlepart and the opening part of the pull tab a rivet island is arranged,that is connected to the central panel by means of the rivet and thatserves as a bending hinge for the pull tab.

It is an object of the invention to provide a can lid for an improvedtwo-piece aluminum beverage can.

According to the invention, this object is achieved by a can lid for analuminum beverage can. The can lid comprises a pull tab. Further, thecan lid has a chuck wall defining a plug diameter, a countersink andcentral panel having a panel radius. On the central panel, a score linedefining a tear panel and a rivet for connecting a pull tab to the canlid are arranged. The rivet extends through a rivet island that isarranged between an opening part of the pull tab and a handle part ofthe pull tab. The lid has lid plug diameter of between 45 to 49 mm, anoutside diameter of between 52 to 55 mm and a weight of less than 1.9gr. The central panel has a thickness of less than 0.19 mm. The scoreline defines an area of between 300 mm² to 350 mm² and the score linehas a shortest distance from the panel radius of less than 3 mm.

Preferably, absorption beads are arranged next to the tear panel and noabsorption bead is provided along a panel radius section, where the tearpanel comes closest to the panel radius at a score line apex.

In preferred embodiment, the rivet is arranged at or near the center ofcentral panel.

Further, it is preferred if the can lid has a rivet island that isfixated to the central panel by means of the rivet. The rivet is tiltedwith respect a normal to a plane defined by countersink. Thus, the axisof rotation defined by rivet is tilted with respect a normal to a planedefined by countersink. The tilt of the rivet facilitates lifting of ahandle part of the pull tab if the pull tab is rotated about the rivet.Accordingly, the handle part may extend to close proximity of the chuckwall and can still be gripped by a user's finger when the pull tab isrotated.

Preferably, the rivet is tilted by an angle of between 1° and 9°, forinstance 2° to 5°, with respect to the normal to the plane defined bythe countersink.

According to a preferred embodiment, the central panel has diameter ofbetween 36 mm and 40 mm.

The can lid preferably has two material adsorption beads that aresymmetrically arranged on both sides of pull tab and tear panel. The twomaterial absorption beads are separated by a bead gap where the tearpanel comes closest to the panel radius at a score line apex.

The pull tab has an axis of symmetry and can rotate around the rivet.Preferably, the axis of symmetry of the pull tab initially is orientatedat an angle of between 5° to 30° with respect to an axis defined by therivet and a centre of the tear panel or the apex of the score line.Accordingly, the pull tab is initially not aligned with the tear paneland therefore first must be aligned prior to opening the tear panel.Aligning the pull tab require a rotation of the pull tab around thetilted rivet which not only results in an alignment of the pull tab withthe tear panel but also results in a lifted handle part of the pull tabthat thus can easier be gripped.

In addition to a tilt of the rivet or as an alternative, at least oneramp-up bead can be provided that is arranged on either side or on bothsides of pull tab. Such ramp can also cause or support a lifting of thehandle part if the pull tab is rotated about the axis of the rivet.Preferably, the ramp-up bead is arranged on the central panel.

Further, one or more orientation beads can be provided that areconfigured and arranged to support aligning of the initially rotatedpull tab in a position suitable for opening the tear panel. Forinstance, such orientation bead can be configured to provide a click-ineffect when the pull is rotated about the rivet and eventually reachesits aligned orientation. The click in effect can be achieved by means ofa gap between two ramp-up beads that receives a part of the pull tab. Insuch embodiment, the ramp-up beads may also serve as orientation beadsthat provide a tactile feedback to a user when the pull-tap isorientated in its oprning position.

The can end is made from sheet metal, for instance from aluminum orsteel that may be pre-coated or plain.

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1 is a side-elevated perspective view of a seamed two-piecebeverage can according to the invention;

FIG. 2 is a cross-sectional view of a seamed two-piece beverage canalong the can's longitudinal axis;

FIG. 3 is a cross sectional view of a can body prior to seaming;

FIG. 4 is a cross sectional view of a can lid prior to seaming;

FIG. 5 is a top-level view of a first embodiment of a can lid accordingto the invention;

FIG. 6 is a top-level view of a second, alternative embodiment of a canlid according to the invention;

FIG. 7 is a top-level view of a third alternative embodiment of a canlid according to the invention;

FIG. 8 is a cross sectional view of an alternative can lid having atilted rivet prior to seaming;

FIG. 9 is a top-level view of a fourth alternative embodiment of a canlid having a pull tab that initially is orientated at an offset-anglewith respect to an axis of symmetry defined by the rivet and the tearpanel and further having ramp-up beads arranged on either side of pulltab that assist lifting the pull tab when the pull tab is rotated aroundan axis of rotation defined by the rivet;

FIG. 10 shows a can lid according to FIG. 9 with the pull tab rotated inits opening position;

FIG. 11 shows details of a first variant of the score line; and

FIG. 12 shows details of a second variant of the score line.

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

FIG. 1 shows a two piece aluminum beverage can 10 according to theinvention. The can comprises a can body 12 and a can lid 14 seamed tothe can body. Can body 12 is a unitary DWI (drawn wall-ironed) can bodyand can lid 14 has a pull tab 38.

The can body 12 is formed from a single piece of sheet metal aluminum(blank) and has a base 16, a cylindrical sidewall 18 and a neck 20. Thebase 16 has a standing ring 22 and a dome 24. Can body 12 is preferablymade from aluminum, in particular from series 3000 aluminum.

The can lid 14 has a chuck wall 26, a countersink 28 and a central panel30. In the central panel, a tear panel 32 is provided which is definedby a score line 34. Next to the tear to panel, a material absorptionbead 36 is arranged. Pull tab 38 is affixed to the central panel 30 bymeans of a rivet 40. A central section of pull tab 38 is a rivet island50 that is fixated to central panel 30 by means of rivet 40. Typically,pull tab 38 can be rotated about rivet 40, if a certain force isapplied. The axis of rotation is perpendicular with respect to a planedefined by rivet island 50 Pull tab 38 has a handle part 42 to begripped by a user's finger and an opening part 44 that is pressedagainst the tear panel 32 if the handle part 42 is lifted by a user.Thus, the pull tab 38 serves to rupture the score line 34 in order toopen the beverage can 10 in a manner known per se. The tear panel 32thus defines the dimensions of the opening created by lifting the handlepart of the pull-tab 38. The tear panel defines an opening—for instancea drinking opening—having an area of between 300 mm² to 350 mm² afteropening the beverage can

Can lid 14 is fixed to can body 12 by means of a folded double seam 41.Seam 41 has a diameter of between 46 mm and 49 mm.

The diameter L of the seam 41 is approximately 48 mm. The diameter J ofthe stand ring 22 is smaller than the diameter L of the seam 41.Therefore, beverage cans can be stacked upon another, so that the standring of the upper can protrudes into the space within seam 41.Alternatively, the stand ring may have a larger diameter than the seam.

Can body 12 has a can body plug diameter of between 45 to 49 mm and aweight below 9.3 g for a 330 ml can, and below 9.7 g for a 355 ml can.

Can lid 14 has a can plug fitting diameter of between 45 to 49 mm, anoutside diameter of between 52 to 55 mm, a central panel with athickness of less than 0.19 mm, e.g. 0.183 mm and a weight of less than1.9 g.

FIG. 2 is a cross-sectional view of can 10 with can lid 14 seamed to canbody 12. In the cross-sectional view, chuck wall 26 and countersink 28of can lid 14 can be seen as well as cylindrical side wall 18, neck 20,stand ring 22 and dome 24 of the can body 12.

Can diameter A is between 56 mm and 59 mm, for instance approximately 58mm. Can diameter A corresponds to the diameter of cylindrical side wall18. As further can be taken from FIG. 3, base 16 extends along a heightF of about 5 to 10 mm. Cylindrical side wall 18 has a height G of about120 mm. Neck 20 has a height H of about 17 mm. Can body 12 is symmetricabout a longitudinal axis 46. Prior to sealing, can body 12 has an upperopen end with an inner diameter B, which is called plug diameter, andwhich is about 46 mm.

Can body 12 is produced by a draw and wall ironing process (DWI),wherein first a cup is formed and then the side wall is formed bydrawing and wall ironing. Thereafter, neck 20 is formed in a neckingmachine (necker) to achieve an upper can end that has a smaller diameterthan the maximum can diameter. The ratio of plug diameter B to candiameter A B/A is called necking ratio. The necking ratio of can body 12of the embodiment of FIG. 3 is a little less than 80%.

Can body 12 is drawn from a single piece of aluminum sheet metal, havinga gauge of 242 μm. Therefore, the wall thickness in the middle of dome24 is approximately 240 μm.

The maximum wall thickness of the can in the middle of the dome of thebase is between 235 μm and 245 μm, such as 240 μm or 242 μm. The toolfor drawing and wall ironing preferably is configured to create atransitional wall thickness from the base to the side wall in two steps.The tool preferably provides a first step with an angle of 1° and asecond step with an angle of ˜30′. Thus, the wall thickness of the canbody is reduced from about 240 μm in the area of the base to about 79 μmat the middle part of side wall 18; cf. mid-side wall thickness C inFIG. 4.

The wall thickness of the middle part of the neck is about 111 μm; cf.mid-neck thickness P in FIG. 4. The neck has a flange (at its upper end)having a wall thickness N (cf. FIG. 4) in the range of between 130 μmand 150 μm, for instance 140 μm.

The transition from side wall 18 to flange 20 is rounded. The radius M(cf. FIG. 4) in the transition from side wall 18 to neck 20 is between10 mm and 20 mm, for instance 15 mm. Such a transition is also called“round shoulder”.

The angle of the neck relative to the side wall 18 of a centrallongitudinal axis of can body 12 is between 25° and 35°, for instance30°.

Beverage can 10 has a nominal volume of between 330 ml and 355 ml and aheight E of approximately of between 145 mm and 147 mm for a 330 ml canand a height E of between 156 mm and 159 mm fora 355 ml can.

A can body according to the embodiments of the Figures has a weightbelow 9.3 g for a can with a nominal volume of 330 ml and below 9.7 gfor a can having a nominal volume of 355 ml.

The total internal volume of the seamed can is the nominal volume plus ahead space. The volume of the head space is little less than 20 ml, forinstance 18 ml. Thus, a can with a nominal volume of 330 ml has a totalinternal volume of 348 ml, and a can with a nominal volume of 355 ml hasa total internal volume of 373 ml.

FIG. 4 is a cross-sectional view of can lid 14 prior to seamingillustrating the outside diameter (curl diameter) K. FIG. 4 furtherillustrates a can lid plug diameter R that is defined by chuck wall 26and a central panel diameter Q of central panel 30.

FIG. 5 is a top-level view of a first embodiment of a can lid accordingto the invention. Can lid 14 as illustrated in FIG. 5 has a curldiameter Q of 53.31 mm, a can lid plug diameter R of 45.4 mm and centralpanel diameter Q of 37.55 mm. As can be taken from FIG. 5, on a centralpanel 30, a central rivet 40 is arranged that connects a rivet island 50of pull tab 38 to central panel 30. Rivet island 50 is an integral partof pull tab 38 and forms a bendable hinge between handle part 42 of pulltab 38 and an opening part 44 of pull tab 38. An outer curl 54 of pulltab 38 provides for sufficient stiffness between handle part 42 andopening part 44 so that opening part 44 can exert strong enough a forceon tear panel 32 when the handle part 42 of pull tab 38 is lifted. Tearpanel 32 is defined by a score line 34 and has an area of 331 mm² andhas a shark fin design featuring a triangular extension 56 next to therivet that improves pouring because it eases entering of air in the can.The closest distance between panel radius 48 and score line 34 of theembodiment of can lid 14 as shown in FIG. 5 is 1.1 mm. Can lid 14 ismade from pre-coated aluminum sheet metal.

FIG. 6 is a top-level view of a second, alternative embodiment of a canlid 14′. The embodiment of can lid 14′ as illustrated in FIG. 6 differsfrom can lid 14 as illustrated in FIG. 5 only by the shape of tear panel14′ that's defined by a score line 34′. The area of tear panel 14′ is334.2 mm². The closest distance between score line 34′ and panel radius38 is 0.99 mm. The distance between score line 34′ and panel radius 38at the apex of score line 34′ is 1.41 mm. The apex of the score line islocated on the axis of symmetry defined by the rivet and the tear panel.

FIG. 7 is a top-level view of a can lid 14″ similar to can lid 14 ofFIG. 5 or can lid 14′ of FIG. 6 that features two material absorptionbeads 36 that are symmetrically arranged on both sides of pull tab 38and tear panel 32. The two material absorption beads 36 are separated bya bead gap 52 where the tear panel comes closest to the panel radius,e.g. at a score line apex. That means, no material absorption bead isprovided where the tear panel 32 comes closest to the panel radius 48.

In order to improve the accessibility of handle part 42 of pull tab 38,rivet 40 may be tilted as shown in FIG. 8. The axis of rotation definedby rivet 40 is tilted with respect a normal to a plane defined bycountersink 28. Likewise the plane defined by rivet island 50 has a tiltangle with respect to the plane defined by countersink 28. The tiltangle is between 2° and 4°, for instance 3°.

Additionally or alternatively can lid 14 can have a pull tab thatinitially is orientated at an offset-angle with respect to an axis ofsymmetry defined by the rivet and the tear panel as shown in FIG. 9. Insuch embodiment, pull-tab 38 first must be aligned with tear panel 32 inorder to allow opening of tear panel 32. Aligning of pull tab 38requires a rotation of pull tab 38 that can help to lift the handle part42 of pull tab 38 so that handle part 42 can be gripped easier.

Lifting of the handle part 42 of pull tab 38 can be facilitated byramp-up beads 58 arranged on either side of pull tab 38; see FIG. 9.Ramp-up beads 58 assist lifting the pull tab when the pull tab isrotated around an axis of rotation defined by the rivet.

Ramp-up beads 58 define a gap between them that provides a click-ineffect when the pull-tab is aligned in its opening position asillustrated in FIG. 10. Thus, ramp-up beads 58 provide a tactilefeedback to a user that helps the user to correctly orientate thepull-tab 38 for opening the tear panel 22. Accordingly, ramp-up beads 58also serve as orientation beads.

FIGS. 11 and 12 show cross-sections of alternative embodiments of scoreline 34 or 34′, respectively. In the embodiment shown in FIG. 11, ananti fracture score 60 is provided that runs in parallel to score line34. Anti fracture score 60 has the effect to lower the tensile stressnear the deepest portion of score line 34 and thus avoids an unwantedfracture of the score line prior to intended opening of tear panel 32.In the alternative embodiment shown in FIG. 12, a background penetration62 is provided that runs along score line 34. Similar to the antifracture score 60 of FIG. 11, background penetration 62 has the effectto lower the tensile stress near the deepest portion of score line 34and thus avoids an unwanted fracture of the score line prior to intendedopening of tear panel 32.

LIST OF REFERENCE NUMERALS

-   10 Can-   12 Can body-   14 Can lid-   16 Base-   18 Side wall-   20 Neck-   22 Stand ring-   24 Dome-   26 Chuck wall-   28 Countersink-   30 Central panel-   32 Tear panel-   34 Score line-   36 Absorption bead-   38 Pull Tab-   40 Rivet-   41 Double Seam-   42 Handle part-   44 Opening part-   46 Longitudinal axis of can body-   48 Panel radius-   50 Rivet island-   52 Bead gap-   54 Pull tab curl-   56 triangular extension(shark fin)-   58 Ramp-up bead-   60 anti fracture score-   62 background penetration-   A Maximum diameter-   B Plug diameter-   A/B Necking Ratio-   C Wall thickness-   D Flange wall thickness-   E Can height-   F Base height-   G Cylindrical sidewall height-   H Neck height-   J Stand ring diameter-   K Curl diameter-   L Seam diameter-   M Shoulder radius-   N Flange thickness-   P Neck thickness-   Q Central panel diameter-   R Can lid plug diameter

What is claimed is:
 1. A can lid for an aluminum beverage can,comprising: a curl for interconnecting the can lid to a neck of thealuminum beverage can; a chuck wall extending inwardly from the curl; acountersink interconnected to the chuck wall; and a central panelinterconnected to the countersink and having a panel radius, a diameterthat is not greater than approximately 40 mm, a score line defining atear panel and a rivet for connecting a pull tab to the can lid; whereinthe score line defines a tear panel that has an area of betweenapproximately 24% to approximately 34% of an area of the central paneland the score line has a shortest distance from the panel radius of lessthan approximately 3 mm.
 2. The can lid according to claim 1, whereinabsorption beads are arranged next to the tear panel and no absorptionbead is provided along a panel radius section where the tear panel comesclosest to the panel radius.
 3. The can lid according to claim 1,wherein the rivet is arranged at or near a center of the central panel.4. The can lid according to claim 1, wherein the pull lab has a rivetisland that is affixed to the central panel by the rivet and wherein therivet is tilted with respect to a line normal to a plane defined by thecountersink.
 5. The can lid according to claim 4, wherein the rivet istilted by an angle of between approximately 1° and 9° with respect tothe line normal to the plane defined by the countersink, or wherein therivet island defines a plane that is tilted by an angle of betweenapproximately 2° and approximately 4° with respect to the plane definedby the countersink.
 6. The can lid according to claim 1, wherein thetear panel has an area of less than approximately 350 mm².
 7. The canlid according to claim 1, further comprising two material adsorptionbeads that are symmetrically arranged on both sides of the pull tab andthe tear panel, the two material absorption beads being separated by abead gap where the tear panel comes closest to the panel radius.
 8. Thecan lid according to claim 1, wherein the pull tab has an axis ofsymmetry and can rotate about the rivet, and wherein the pull tabinitially is orientated in a stored position with the axis of symmetryof the pull tab at an angle of between approximately 5° to 30° withrespect to an axis of symmetry defined by the rivet and the tear panel.9. The can lid according to claim 8, further comprising at least oneramp-up bead arranged on either side of the pull tab or on both sides ofthe pull tab to elevate a lift end of the pull tab, the at least oneramp-up bead extending substantially parallel to a perimeter of thecentral panel.
 10. The can lid according to claim 9, further comprisingat least two ramp-up beads that define a gap between them, wherein thegap is configured to provide a tactile feedback to the user when thepull tab is rotated from a stored position off-set from the ramp upbeads and reaches an opening position suitable for opening the tearpanel (32).
 11. The can lid according to claim 1, wherein the shortestdistance between the score line and the panel radius is less thanapproximately 1.1 mm.
 12. The can lid according claim 1, wherein the canend is made from an aluminum or a steel.
 13. A beverage can, comprising:a body that is symmetric about a longitudinal axis and includes: a baseend with a stand ring and a dome; a sidewall extending upwardly from thebase end; and a neck; and a can lid interconnected to an upper end ofthe neck by a seam, the can lid including: a chuck wall extendingdownwardly from the seam; a countersink at a lower portion of the chuckwall; and a center panel interconnected to an inner portion of thecountersink, the center panel having a panel radius, a score linedefining a tear panel, a rivet, a pull tab interconnected to the centerpanel by the rivet, and at least one ramp-up bead configured to elevatea grip end of the pull tab away from the center panel as the pull tab isrotated from a stored position to an opening position, wherein theramp-up bead has an arcuate shape and is positioned substantiallyparallel to a perimeter of the center panel, and wherein a distancebetween a portion of the score line and the center panel perimeter isless than approximately 1.1 mm.
 14. The beverage can of claim 13,wherein the distance between the portion of the score line and thecenter panel perimeter is less than approximately 1 mm.
 15. The beveragecan of claim 13, wherein the tear panel has an area of betweenapproximately 24% to approximately 34% of an area of the center panel.16. The beverage can of claim 13, wherein the pull tab is configured torotate around the rivet from the stored position with an opening endrotated away from the tear panel to the opening position with theopening end positioned above the tear panel and with the grip end of thepull tab spaced from the center panel.
 17. The beverage can of claim 13,wherein the rivet is tilted at an angle of between approximately 1° and9° with respect to a line normal to a plane defined by the countersink.18. The beverage can of claim 13, wherein the pull tab has a rivetisland affixed to the rivet, wherein the rivet island defines a planethat is tilted at an angle of between approximately 2° and approximately4° with respect to a plane defined by the countersink.
 19. The beveragecan of claim 13, further comprising a background penetration formed inthe center panel that is configured to lower a tensile strength of thescore line, the background penetration positioned along both sides ofthe score line.
 20. The beverage can of claim 19, wherein the backgroundpenetration further comprises a first width and a first depth, andwherein the first width is greater than a widest portion of the scoreline and the first depth is less than a maximum depth of the score line.